1. Field of the Invention
Subject of the present invention is a safety device for electrical openers for a vehicle, especially window lifters of the cable or swing-arm/toothed-sector type and sunroofs, comprising a motor, a movable member, and a kinematic chain for driving this movable member by the motor.
2. Description of the Related Art
Currently, there are known to exist three types of window lifter on motor vehicles: window lifters of the rack-cable type, window lifters of the twisted-cable (Bowden cable) type and window lifters of the am and toothed-sector type. The invention relates to these window lifters and to other electrical openers having similar operating conditions, most particularly to sunroofs which are driven by cables.
When an obstacle lies in the path for closing the window (or the sunroof), the system must recognize the presence of an abnormal phenomenon and, if the load on the window or the sunroof exceeds a limiting value, the window must not continue its travel, but stop and at least free the load. This freeing of the load may be obtained either by freeing the window which is lowered under a small load or under the effect of its own weight if the friction in the lateral seal allows it, or by reversing the motion of the window, which is then forcibly lowered.
In order to solve this problem, various electronic and electromechanical safety devices have already been proposed which have, among other drawbacks, that of being relatively expensive by reason of their complexity. This high cost of manufacturing is obviously an obstacle to their widespread use.
Moreover, U.S. Pat Nos. 2,130,764 and 2,461,085 describe swing-door safety devices in which switches work upon closing. Consequently, if the wiring is defective, the safety system does not operate.
Furthermore, these two prior devices include springs, the working travel of which is great, and therefore the sensitivity to tripping is low.